There are devices for dispensing fluids that contain, for example, insulin or other medicinal preparations, which can be worn by a user or patient so as to enable dispensing of the fluid continuously or when necessary.
For these types of devices, it is very important to implement control of the flow of the fluid medicine continuously in order to guarantee effectiveness of treatment and safety of the patient in the event of any malfunctioning, such as leaks, air bubbles, occlusions, etc.
There are known systems for this purpose made up of two parts. A fixed part includes the electronic-control part, the memory, and the radio frequency interface, and can, for example, be worn by the user. A replaceable part includes the reservoir for the medicine, the micro-pump of a MEMS (microelectromechanical system) type, with the corresponding actuator and the battery that supplies the actuator.
In greater detail, in this connection, FIG. 1 illustrates a device for dispensing a fluid 10 that comprises a replaceable part 20, which in turn comprises a reservoir 21, a MEMS micro-pump 22 which receives through an inlet duct 21a the fluid from the reservoir 21, and is associated to a pressure sensor 23. The device 10 also includes an actuator 24 and a battery 25. A fixed part 30 comprises an electronic control module 31, which in turn comprises a memory 32 and a communication interface operating at a radio frequency 33.
Designated by 11 is a signal connection between the pressure sensor 23 and the electronic module 31, whereas designated by 12 is a fluid dispensing conduit that from the micro-pump 22, through the fixed part 31, reaches a dispensing needle 13 for dispensing the fluid medicine into the body of the subject who is wearing the fluid-dispensing device 10.
Designated by 26 is a terminal of the actuator 24, for example, the shaft or punch of a linear actuator, which operates the micro-pump 22. The micro-pump 22 in general comprises a pumping chamber, the top wall of which is constituted by a membrane. The terminal 26 periodically exerts mechanical pressure on the membrane of the pump 22.
Control of the flow is carried out via control of the pumping pressure on the MEMS micro-pump, via the pressure sensor (or sensors) 23 present on the MEMS micro-pump 22.
The signal of the pressure sensor 23 is transferred to the substrate of the micro-pump 22 via wire bonding or by a connection of some other type (microjunctions obtained by remelting of a soldering alloy pre-deposited on the MEMS, or by dispensing conductive glue, or by thermosonic remelting of the contacts of the micro-pump on those of the substrate). From the substrate of the micro-pump the pressure signals are transferred, on the signal connection 11, to the electronic-control part 31 on the fixed part 30. This implements signal connection 11 via sliding contacts or spring contacts.
As illustrated in FIG. 1A, the micro-pump 22 comprises a pumping chamber 22a made up of three different silicon layers set on top of a silicon substrate 22d, of which the two extreme ones constitute a bottom layer 22e and a roof layer or lid 22f of the micro-pump 22, and which identify between them a chamber layer 22i, dug in which is the pumping chamber 22a. The inlet duct 21a and the outlet towards the fluidic or fluid dispensing conduit 12 must be arranged on the bottom layer 22e of the micro-pump 22 in order to be able to interface the substrate 22d since the structure of the two valves, 21b on the inlet duct 21a and 12b on the outlet represented by the fluid dispensing conduit 12, entails that these cannot be made on a single silicon layer, but must, instead, each be made on a different layer, the bottom layer 22e and the top layer 22f. Consequently, the process is aimed at obtaining that the outlet circuit from the pumping chamber 22a passes through the roof layer 22f and is then brought back onto the bottom layer 22e by forming a channel 22g on the roof layer 22f, which is sealed via a lid element 22h. 
The above device presents some drawbacks in so far as the architecture, in particular with respect to the replaceable part which is complex, and the arrangement of the pressure sensor which requires arrangement inside the MEMS micro-pump of circuits and bonding pads. Furthermore, such an arrangement involves channels made on the surface of the pump or in a layer where the pump itself is provided.